This invention relates to abrasive structures for use in the so-called stone washing of fabrics and garments. More particularly, this invention relates to substantially form retaining blocks of material having resilient abrasive surfaces to be used in stone washing processes and to methods for washing fabrics and garments to achieve the controlled abrasion of those garments.
There has arisen in recent years an industry, related to the laundering industry, known as "stone washing." Stone washing is the term used to describe methods for imparting a soft, worn look to new clothes, in particular, denim jeans. Consumers will pay a significant premium for clothes having a soft, worn look, and accordingly, a number of methods have been developed by prior workers for washing new garments and fabrics to cause them to have the desired feel and appearance.
Among the prior art methods employed for stone washing are those wherein large pumice stones, i.e., stones 2 to 4 inches or more in diameter, are used in the washing machine. These large stones circulate with the garments during the wash cycle and cause the garments to abrade and soften. There are major problems with this method, however, among them being that the stones break, they collide with the washing cylinder during agitation and cause damage thereto, and, most importantly, they cause damage to the garments themselves. The latter is caused, it is believed, when pumice stones strike one another or strike the washing cylinder and a garment or portion thereof is caught in between. This creates holes in the garments and makes them unsuitable for sale. The pumice stones have also been known to break and form sharp edges and points and these also cause damage to the garments and the washing machine. Still another disadvantage of the pumice stone method is that it is time consuming and labor consuming to remove the stones from the wash cylinder after each cycle and it is inconvenient, if not dangerous, to workers handling the sharp stones. Yet another disadvantage of stone washing methods employing pumice stones is that the stones themselves or fragments thereof actually find their way into the pockets of the garments being washed and they must be removed in a time consuming and labor intensive operation.
A second unsatisfactory method of stone washing involves the abrasion of the wash cylinder by abrasive materials such as volcanic rock. The rough, abraded cylinder surface then contacts the garments during the wash cycle and causes the desired wear and abrasion of the garments. The disadvantages of this method include the time and cost of repeated resurfacings of the wash cylinder and the substantial time and energy required to achieve satisfactory stone washing of the garments in the machine.
A further disadvantage of both prior art methods is that the garments rub against the pumice stones or the wash cylinders where they have been creased and folded during manufacture. The creased and folded areas are worn to a substantially greater degree than the balance of the garment and this results in streaking, unacceptable appearance and sometimes excessive wear of the garment at the crease lines. Garments treated in different stone washing cycles may have different appearance, nap, streaking and wear, and even garments washed in a given cycle may have different appearances as well.
A recent process for stone washing garments is that described in U.S. Pat. No. 4,575,887 wherein a predetermined amount of pumice sand or other small-sized particle abrasive is used to abrade and clean the garments. After agitation in the wash medium containing the pumice sand or like material, the washing machine receptacle is drained and the abrasive material is trapped and separated from the drainage liquid. The filtered abrasive particles are reused in subsequent operations.
The major disadvantage of the processes described in the '887 patent include the abrasion of the inside wall of the cylinder, the costs and time involved in filtering out the pumice from the wash liquid, the need to have one or more subsequent rinse steps to remove the pumice from the garments after the abrasion step, and the formation of pumice deposits in the pockets of garments such as jeans. In addition, there is constant attrition and loss of abrasive material, substantial quantities of abrasive material must be used in each cycle per unit weight of fabric being stone washed (for example, from one to two pounds of pumice sand per pound of garments) and there is a significant rate of deterioration of the commercial washers used to process the garments.
It is thus a primary object of this invention to provide an abrasive structure for use in stone washing of fabrics and garments which is more convenient to handle and more effective in use than the pumice stones, abraded cylinders, and pumice sand of the prior art.
It is a further and related object of this invention to provide an abrasive structure which is easy and inexpensive to manufacture, which can be reused in multiple stone washing cycles and which is not difficult or dangerous to handle.
It is still a further object of this invention to provide an abrasive structure having a uniform abrasive surface which will not damage or excessively wear fabrics and garments being subjected to the stone washing method, which will not deteriorate during use, and which will provide uniformly stone washed garments having a consistent nap and a low level amount of textile wear.
It is a further object of this invention to provide processes for stone washing garments, particularly denim garments, as well as fabrics in general, which are less wearing on the commercial washing equipment, which employ reduced amounts of abrasive material such that energy requirements are less and which provide satisfactory and uniform wear characteristics on the garments which are washed.